This invention relates to a digital cash safe used in- an electronic transaction system for transferring digital cash to a memory device provided by a payee from a card owned by a payer.
An electronic transaction system using a prepaid microchip card is disclosed in U.S. Pat. No. 4,877,947. The patented system employs a customer's microchip card in which the customer's monetary value is digitally stored. A vendor's microchip card is also provided in which the vendor's monetary value is digitally stored. When a purchase is made, the customer inserts his card in a customer's microchip card reader/writer. The vendor inserts bis microchip card in a vendor's microchip card reader/writer and enters the amount of the purchase on a keypad connected to the vendor's microchip card reader/writer. The amount of the purchase is communicated from the vendor's microchip card reader/writer to the customer's microchip card reader/writer, and then from the two microchip card reader/writers to both microchip cards. With suitable verifications, the amount of the purchase is deducted from the balance recorded in the customer's microchip card and added to the balance recorded in the vendor's microchip card.
Electronic transaction systems have many advantages over cash payment systems. However, a problem faced by large commercial facilities such as department stores and banks is that they must frequently carry out simultaneously a plurality of transactions using digital cash. Consequently, it is necessary to prepare in advance a plurality of microchip cards which require a relatively large amount of space for storage. To solve this problem, our invention provides an electronic transaction system which permits the efficient and secure storage of many microchip cards in a limited space, and which may be used for carrying out a plurality of transactions at the same time.